The Animal Resource Core, together with its main component, the Animal Records Review Committee (ARRC), is that part of the Program Project which is responsible for (1) screening the Yerkes rhesus population in order to select and purchase animals for inclusion in the Program and (2) monitoring those animals throughout the conduct of the project to ensure their continuing suitability. The Core will review the health records of all animals prior to entry into the study to determine if they meet the selection criteria developed jointly by staff members of the NIH and the Program Project. It will also review the health status of all monkeys in the Program on a regular basis to insure that their continued use by the program project is appropriate. The Core will be responsible for the decision to terminate an animal promptly should medical or health conditions warrant. The Animal Core will also have the task of assigning and scheduling animals to behavioral testing, PET and MR imaging and physical exams in an efficient and coordinated manner. The Core will receive and review complete necropsy reports including histopathological assessment of all major organ systems. This is to ensure that no extra neural disease processes that may interact with aging variables being examined in this Program can confound our results. Our neuropathologist will review results of the postmortem autopsies and pathological surveys to determine whether occult problems, the nature of which would warrant exclusion from the data analysis, were present. Finally, the Core will ensure prompt, thorough, and efficient access to all records and to disseminate the decisions of the Core to the remaining scientific personnel of the Program Project. The Core will also collect all data from health records and postmortem examination and will enter them in our unified database for subsequent overall statistical analysis.